Glue holds a lot of things together. Your kid’s art projects, the piece of your favorite coffee mug that broke off, and it’s probably also used in the construction of the shoes you’re wearing.
And it’s that last one that keeps us up at night. Because the heavy-duty adhesives used to attach the sole to the rest of the shoe contain toxic solvents. These adhesives also deteriorate over time, causing the sole to separate (or “delaminate” as we say in the shoe industry). It’s one of the main reasons shoes fall apart.
We're working to eliminate the use of solvents and make delamination a thing of the past with KEEN.FUSION technology. It uses heat and pressure instead of toxic glues to mechanically bond the sole to the upper. You’ll find it in our Targhee IV hikers, KNX sneakers, and all American Built work boots.
First you need special shoemaking machinery for what’s called a direct-injection process, something we invested in years ago. We have this machinery in our Portland, Oregon, and Thailand factories. With this machine, the midsole is injected between the upper and the outsole, fusing the whole shoe together.
Here's a short animation to see how it works:
The midsole is what gives you supportive cushioning adventure after adventure. In this case, it also creates a longer-lasting bond for even more adventures. A win-win for you and the planet.
KEEN.FUSION uses heat and pressure to create a mechanical bond that won’t separate. In independent tests, a Targhee IV boot made with KEEN.FUSION was flexed 1,000,000 times, which translates to about 500 miles (or 1,000 miles per pair of boots). Then it was loaded into a “pull” test machine, which uses clamps at various points around the midsole to test how much force is required to separate the midsole from the upper. On average, it took 3X our passing standard of force – or 3X the bonding power of glue – to separate the upper from the midsole.
There are 8 billion people in the world and 24 billion pairs of shoes made every year. When we can make a shoe last longer for our fans, that’s fewer shoes they need to buy, and fewer shoes that need to use Earth’s resources to be made. Our KEEN.FUSION construction process is better for people and the planet in a few ways: it fuses the upper to the sole for a longer-lasting bond and it does it without any toxic glues. It also uses less energy.
"We’re on a mission to make the world’s cleanest, longest-lasting shoes. We call it Consciously Created, and KEEN.FUSION is a big step forward on our journey."
Data we’ve collected from our owned factories suggest that KEEN.FUSION construction requires 3.5X less electricity use per pair than traditional cement construction (aka glue). It also emits almost 1kg less CO₂e (carbon dioxide equivalent or greenhouse gas emissions) than traditional cement construction – primarily due to using less energy and no solvents in the outsole/midsole construction.
We’re on a mission to make the world’s cleanest, longest-lasting shoes. We call it Consciously Created, and KEEN.FUSION is a big step forward on our journey. Because durability is sustainability, and so is reducing the use of energy and solvents. More to come.
